According to the `ld.so` [manpage][1], it is a space separated list.  So:
&lt;pre&gt;
LD_PRELOAD=&quot;path1 path2&quot;
&lt;/pre&gt;
ought to work.


  [1]: http://kernel.org/doc/man-pages/online/pages/man8/ld.so.8.html

One option is to have the overridden version of both `getpid` and `getid` in a single `.so` which you give to `LD_PRELOAD`.

I am trying to check Internet connectivity on Android using the following method. I have a Wi-Fi connection.

    private boolean checkInternetConnection() {
        ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

        // Test for connection
        if (cm.getActiveNetworkInfo() != null
                &amp;&amp; cm.getActiveNetworkInfo().isAvailable()
                &amp;&amp; cm.getActiveNetworkInfo().isConnected()) {
            return true;
        }
        else {
            // No conection
            return false;
        }
    }

I disconnect my PC from the Internet and then try to run the above method. Still it always returns true!? Why?


How do I disable the Internet connection in Android Emulator?

I have a WebElement, I want to reset its an attribute&#39;s value to some other value (for e.g. `attr` is the attribute, and I want to change its original `value=1` to new `value=10`). 

Is it possible? I am using Selenium 2.0 (WebDriver.) 


Selenium: Can I set any of the attribute value of a WebElement in Selenium?

I know how to override one library with LD_PRELOAD, for example, as follows.

    LD_PRELOAD=./getpid.so ./testpid

Now my question is how to override multiple files. Say I want to override both getpid and getid, how would I specify that?

Specifying multiple files with LD_PRELOAD

<p>I know how to override one library with LD_PRELOAD, for example, as follows.</p>
<pre><code class="hljs language-bash">LD_PRELOAD=./getpid.so ./testpid
</code></pre>
<p>Now my question is how to override multiple files. Say I want to override both getpid and getid, how would I specify that?</p>


&gt; No, I don&#39;t want to use **ncurses**, because I want to learn how the
&gt; terminal works and have fun programming it on my own. :) It doesn&#39;t
&gt; have to be portable, it has to work on linux xterm-based terminal emulators only.

What I want to do is programming an interactive terminal application like htop and vim are. What I mean is not the output of characters which look like boxes or setting colors, this is trivial; also to make the content fit to the window size. What I need is

 1. how to get **mouse interactions** like clicking on a character and scrolling the mouse wheel (when the mouse is at a specific character) to implement scrolling [**EDIT: in a terminal emulator of course**], and

 1. how to completely **save and restore** the output of the parent process and seperate my printing from its output, so after leaving my application nothing but the command I entered in the shell should be there, like when running htop and quitting it again: nothing is visible from this application anymore.

I really don&#39;t want to use ncurses. But of course, if you know which part of ncurses is responsible for these tasks, you&#39;re welcome to tell me where in the source code I can find it, so I will study it.

Writing a &quot;real&quot; interactive terminal program like vim, htop, ... in C/C++ without ncurses

The standard predefined macro `__FILE__` available in C shows the full path to the file. Is there any way to short the path? I mean instead of

    /full/path/to/file.c

I see

    to/file.c

or 

    file.c

__FILE__ macro shows full path

So the reason for `typedef`:ed primitive data types is to abstract the low-level representation and make it easier to comprehend (`uint64_t` instead of `long long` type, which is 8 bytes). 

However, there is `uint_fast32_t` which has the same `typedef` as `uint32_t`. Will using the &quot;fast&quot; version make the program faster?


What is uint_fast32_t and why should it be used instead of the regular int and uint32_t?


I am going through an eg pgm to create a make file.

http://mrbook.org/tutorials/make/


My folder eg_make_creation contains the following files,

    desktop:~/eg_make_creation$ ls
    factorial.c  functions.h  hello  hello.c  main.c  Makefile

Makefile
--------

    # I am a comment, and I want to say that the variable CC will be
    # the compiler to use.
    CC=gcc
    # Hwy!, I am comment no.2. I want to say that CFLAGS will be the
    #options I&#39;ll pass to the compiler
    CFLAGS=-c -Wall
    
    all:hello
    
    hello:main.o factorial.o hello.o
      $(CC) main.o factorial.o hello.o -o hello
    
    main.o:main.c
      $(CC) $(CFLAGS) main.c
    
    factorial.o:factorial.c
      $(CC) $(CFLAGS) factorial.c
    
    hello.o:hello.c
      $(CC) $(CFLAGS) hello.c
    
    clean:
      rm -rf *o hello

error:

    desktop:~/eg_make_creation$ make all
    make: Nothing to be done for `all&#39;.

Please help me understand to compile this program.




make: Nothing to be done for `all&#39;

    struct _USBCHECK_FLAGS
    	{
    		unsigned char	DEVICE_DEFAULT_STATE	   : 1;
    		unsigned char	DEVICE_ADDRESS_STATE 	   : 1;
    		unsigned char	DEVICE_CONFIGURATION_STATE : 1;
    		unsigned char	DEVICE_INTERFACE_STATE	   : 1;
    		unsigned char	FOUR_RESERVED_BITS		   : 8;
    		unsigned char	RESET_BITS		           : 8;
    	} State_bits;

What does `:1` and `:8` mean?



&quot;:&quot; (colon) in C struct - what does it mean?

I&#39;m trying to use the `cp` command and force an overwrite.

I have tried `cp -rf /foo/* /bar`, but I am still prompted to confirm each overwrite.

How to force cp to overwrite without confirmation

I have an email dump of around 400mb. I want to split this into .txt files, consisting of one mail in each file. Every e-mail starts with the standard HTML header specifying the doctype.

This means I will have to split my files based on the above said header. How do I go about it in linux?

Splitting a file in linux based on content

How can I permanently change the disassembly flavor in GDB.  I tried:`set disassembly-flavor intel` in GDB, but when I fire up GDB later it still has the att flavor.

Permanently Change Disassembly Flavor in GDB

I have following string:

    {&quot;_id&quot;:&quot;scheme_version&quot;,&quot;_rev&quot;:&quot;4-cad1842a7646b4497066e09c3788e724&quot;,&quot;scheme_version&quot;:1234}

and I need to get value of &quot;scheme version&quot;, which is 1234 in this example.

I have tried 

    grep -Eo &quot;\&quot;scheme_version\&quot;:(\w*)&quot;

however it returns 

    &quot;scheme_version&quot;:1234

How can I make it? I know I can add **sed** call, but I would prefer to do it with single grep.

grep: group capturing

Say you have a txt file, what is the command to view the top 10 lines and bottom 10 lines of file simultaneously?

i.e. if the file is 200 lines long, then view lines 1-10 and 190-200 in one go. 

unix - head AND tail of file

I have a string, say: `abc.def.ghi.jkl.myfile.mymethod`. How do I dynamically import `mymethod`?

Here is how I went about it:

    def get_method_from_file(full_path):
        if len(full_path) == 1:
            return map(__import__,[full_path[0]])[0]
        return getattr(get_method_from_file(full_path[:-1]),full_path[-1])
    
    
    if __name__==&#39;__main__&#39;:
        print get_method_from_file(&#39;abc.def.ghi.jkl.myfile.mymethod&#39;.split(&#39;.&#39;))




I am wondering if the importing individual modules is required at all.

Edit: I am using Python version 2.6.5.

Dynamically import a method in a file, from a string

A dynamically-added script is not showing up in the browser&#39;s debugger&#39;s scripts section.

Explanation:

I need to use and have used

    if( someCondition == true ){
       $.getScript(&quot;myScirpt.js&quot;, function() {
           alert(&#39;Load Complete&#39;);
           myFunction();
       });
    }

so that myScript.js can be dynamically loaded on meeting some condition...
And myFunction can be called only after getting the whole script loaded...

But browsers are not showing the dynamically loaded myScript.js in their debugger&#39;s script section.

Is there another way round so that all of the goals may be achieved which will make one to be able to debug a dynamically-loaded script there in the browser itself?


How to debug dynamically loaded JavaScript (with jQuery) in the browser&#39;s debugger itself?

I&#39;m trying to use dynamic variable names (I&#39;m not sure what they&#39;re actually called) But pretty much like this:

    for($i=0; $i&lt;=2; $i++) {
        $(&quot;file&quot; . $i) = file($filelist[$i]);
    }
    
    var_dump($file0);

The return is `null` which tells me it&#39;s not working. I have no idea what the syntax or the technique I&#39;m looking for is here, which makes it hard to research. `$filelist` is defined earlier on.

Using braces with dynamic variable names in PHP

I am getting an error that says:

&gt;**&#39;object&#39; does not contain a definition for &#39;Title&#39;**

all the code is also on [github][1]

I have a ConsoleApplication1 that looks like this

    namespace ConsoleApplication1
    {
        class Program
        {
            static void Main(string[] args)
            {
                Movie m = new Movie();
                var o = new { Title = &quot;Ghostbusters&quot;, Rating = &quot;PG&quot; };
                Console.WriteLine(m.PrintMovie(o));
            }
        }
    } 


and *Movie.cs* 



    public class Movie : DynamicObject
    {
        public string PrintMovie(dynamic o)
        {
            return string.Format(&quot;Title={0} Rating={1}&quot;, o.Title, o.Rating);
        }
    } 

it works fine from the SAME project, but if I add ConsoleApplication2 with a reference to ConsoleApplication1 and add the Exact same code






    namespace ConsoleApplication2
    {
        class Program
        {
            static void Main(string[] args)
            {
                Movie m = new Movie();
                var o = new { Title = &quot;Ghostbusters&quot;, Rating = &quot;PG&quot; };
                Console.WriteLine(m.PrintMovie(o));
            }
        }
    }
 
I get an error:

&gt;&#39;object&#39; does not contain a definition for &#39;Title&#39;**

even though it is in the dynamic object.

+		o.Title	&#39;o.Title&#39; threw an exception of type &#39;Microsoft.CSharp.RuntimeBinder.RuntimeBinderException&#39;	dynamic {Microsoft.CSharp.RuntimeBinder.RuntimeBinderException}

Here is a screen shot: ![enter image description here][2]


I am doing something like this and trying to call the movie function from a test project.


  [1]: https://github.com/eiu165/DynamicTest
  [2]: http://i.stack.imgur.com/koHkk.jpg

dynamic does not contain a definition for a property from a project reference

[This article](http://www.linuxjournal.com/node/4540) has a snippet showing usage of `__bases__` to dynamically change the inheritance hierarchy of some Python code, by adding a class to an existing classes collection of classes from which it inherits.  Ok, that&#39;s hard to read, code is probably clearer:

    class Friendly:
        def hello(self):
            print &#39;Hello&#39;

    class Person: pass

    p = Person()
    Person.__bases__ = (Friendly,)
    p.hello()  # prints &quot;Hello&quot;

That is, `Person` doesn&#39;t inherit from `Friendly` at the source level, but rather this inheritance relation is added dynamically at runtime by modification of the `__bases__ `attribute of the Person class.  However, if you change `Friendly` and `Person` to be new style classes (by inheriting from object), you get the following error:

&lt;!-- language: lang-none --&gt;

    TypeError: __bases__ assignment: &#39;Friendly&#39; deallocator differs from &#39;object&#39;

A bit of Googling on this seems to [indicate some incompatibilities](http://wiki.python.org/moin/NewClassVsClassicClass) between new-style and old style classes in regards to changing the inheritance hierarchy at runtime.  Specifically: [&quot;New-style class objects don&#39;t support assignment to their __bases__ attribute&quot;](http://www.python.org/download/releases/2.2.2/bugs/).

My question, is it possible to make the above Friendly/Person example work using new-style classes in Python 2.7+, possibly by use of the `__mro__` attribute?

__*Disclaimer: I fully realise that this is obscure code.  I fully realize that in real production code tricks like this tend to border on unreadable, this is purely a thought experiment, and for funzies to learn something about how Python deals with issues related to multiple inheritance.*__

How to dynamically change base class of instances at runtime?

Suppose `a1`, `b1`, `c1`, and `d1` point to heap memory, and my numerical code has the following core loop.

    const int n = 100000;

    for (int j = 0; j &lt; n; j++) {
        a1[j] += b1[j];
        c1[j] += d1[j];
    }

This loop is executed 10,000 times via another outer `for` loop. To speed it up, I changed the code to:

    for (int j = 0; j &lt; n; j++) {
        a1[j] += b1[j];
    }

    for (int j = 0; j &lt; n; j++) {
        c1[j] += d1[j];
    }

Compiled on [Microsoft Visual C++ 10.0][1] with full optimization and [SSE2][2] enabled for 32-bit on a [Intel Core 2][3] Duo (x64), the first example takes 5.5 seconds and the double-loop example takes only 1.9 seconds.

Disassembly for the first loop basically looks like this (this block is repeated about five times in the full program):

    movsd       xmm0,mmword ptr [edx+18h]
    addsd       xmm0,mmword ptr [ecx+20h]
    movsd       mmword ptr [ecx+20h],xmm0
    movsd       xmm0,mmword ptr [esi+10h]
    addsd       xmm0,mmword ptr [eax+30h]
    movsd       mmword ptr [eax+30h],xmm0
    movsd       xmm0,mmword ptr [edx+20h]
    addsd       xmm0,mmword ptr [ecx+28h]
    movsd       mmword ptr [ecx+28h],xmm0
    movsd       xmm0,mmword ptr [esi+18h]
    addsd       xmm0,mmword ptr [eax+38h]

Each loop of the double loop example produces this code (the following block is repeated about three times):

    addsd       xmm0,mmword ptr [eax+28h]
    movsd       mmword ptr [eax+28h],xmm0
    movsd       xmm0,mmword ptr [ecx+20h]
    addsd       xmm0,mmword ptr [eax+30h]
    movsd       mmword ptr [eax+30h],xmm0
    movsd       xmm0,mmword ptr [ecx+28h]
    addsd       xmm0,mmword ptr [eax+38h]
    movsd       mmword ptr [eax+38h],xmm0
    movsd       xmm0,mmword ptr [ecx+30h]
    addsd       xmm0,mmword ptr [eax+40h]
    movsd       mmword ptr [eax+40h],xmm0

The question turned out to be of no relevance, as the behavior severely depends on the sizes of the arrays (n) and the CPU cache. So if there is further interest, I rephrase the question:

- Could you provide some solid insight into the details that lead to the different cache behaviors as illustrated by the five regions on the following graph?

- It might also be interesting to point out the differences between CPU/cache architectures, by providing a similar graph for these CPUs.

Here is the full code. It uses [TBB][4] `Tick_Count` for higher resolution timing, which can be disabled by not defining the `TBB_TIMING` Macro:

    #include &lt;iostream&gt;
    #include &lt;iomanip&gt;
    #include &lt;cmath&gt;
    #include &lt;string&gt;
    
    //#define TBB_TIMING
    
    #ifdef TBB_TIMING	
    #include &lt;tbb/tick_count.h&gt;
    using tbb::tick_count;
    #else
    #include &lt;time.h&gt;
    #endif
    
    using namespace std;
    
    //#define preallocate_memory new_cont
    
    enum { new_cont, new_sep };
    
    double *a1, *b1, *c1, *d1;
    
    
    void allo(int cont, int n)
    {
    	switch(cont) {
    	  case new_cont:
    		a1 = new double[n*4];
    		b1 = a1 + n;
    		c1 = b1 + n;
    		d1 = c1 + n;
    		break;
    	  case new_sep:
    		a1 = new double[n];
    		b1 = new double[n];
    		c1 = new double[n];
    		d1 = new double[n];
    		break;
    	}

    	for (int i = 0; i &lt; n; i++) {
    		a1[i] = 1.0;
            d1[i] = 1.0;
            c1[i] = 1.0;
            b1[i] = 1.0;
        }
    }
    
    void ff(int cont)
    {
    	switch(cont){
    	  case new_sep:
    		delete[] b1;
    		delete[] c1;
    		delete[] d1;
    	  case new_cont:
    		delete[] a1;
    	}
    }
    
    double plain(int n, int m, int cont, int loops)
    {
    #ifndef preallocate_memory
    	allo(cont,n);
    #endif
    
    #ifdef TBB_TIMING	
    	tick_count t0 = tick_count::now();
    #else
    	clock_t start = clock();
    #endif
    	    
    	if (loops == 1) {
    		for (int i = 0; i &lt; m; i++) {
    			for (int j = 0; j &lt; n; j++){
    				a1[j] += b1[j];
    				c1[j] += d1[j];
                }
    		}
    	} else {
    		for (int i = 0; i &lt; m; i++) {
    			for (int j = 0; j &lt; n; j++) {
    				a1[j] += b1[j];
    			}
    			for (int j = 0; j &lt; n; j++) {
    				c1[j] += d1[j];
    			}
    		}
        }
    	double ret;
    
    #ifdef TBB_TIMING	
    	tick_count t1 = tick_count::now();
    	ret = 2.0*double(n)*double(m)/(t1-t0).seconds();
    #else
    	clock_t end = clock();
    	ret = 2.0*double(n)*double(m)/(double)(end - start) *double(CLOCKS_PER_SEC);
    #endif
    	
    #ifndef preallocate_memory
    	ff(cont);
    #endif
    
    	return ret;
    }
    
    
    void main()
    {	
    	freopen(&quot;C:\\test.csv&quot;, &quot;w&quot;, stdout);
    
    	char *s = &quot; &quot;;
    
    	string na[2] ={&quot;new_cont&quot;, &quot;new_sep&quot;};
    
    	cout &lt;&lt; &quot;n&quot;;
    
    	for (int j = 0; j &lt; 2; j++)
    		for (int i = 1; i &lt;= 2; i++)
    #ifdef preallocate_memory
    			cout &lt;&lt; s &lt;&lt; i &lt;&lt; &quot;_loops_&quot; &lt;&lt; na[preallocate_memory];
    #else
    			cout &lt;&lt; s &lt;&lt; i &lt;&lt; &quot;_loops_&quot; &lt;&lt; na[j];
    #endif
    			
    	cout &lt;&lt; endl;
    
    	long long nmax = 1000000;
    
    #ifdef preallocate_memory
    	allo(preallocate_memory, nmax);
    #endif
    	
    	for (long long n = 1L; n &lt; nmax; n = max(n+1, long long(n*1.2)))
        {
    		const long long m = 10000000/n;
    		cout &lt;&lt; n;

    		for (int j = 0; j &lt; 2; j++)
    			for (int i = 1; i &lt;= 2; i++)
    				cout &lt;&lt; s &lt;&lt; plain(n, m, j, i);
    		cout &lt;&lt; endl;
    	}
    }

It shows FLOP/s for different values of `n`.

[![Performace chart][5]][5]


  [1]: http://en.wikipedia.org/wiki/Visual_C++#32-bit_versions
  [2]: http://en.wikipedia.org/wiki/SSE2
  [3]: http://en.wikipedia.org/wiki/Intel_Core_2
  [4]: https://www.threadingbuildingblocks.org/
  [5]: https://i.stack.imgur.com/426bP.gif

Why are elementwise additions much faster in separate loops than in a combined loop?

I saw some x86 assembly in Qt&#39;s source:

    q_atomic_increment:
    	movl 4(%esp), %ecx
    	lock 
    	incl (%ecx)
    	mov $0,%eax
    	setne %al
    	ret
    
    	.align 4,0x90
    	.type q_atomic_increment,@function
    	.size	q_atomic_increment,.-q_atomic_increment

1. From Googling, I knew `lock` instruction will cause CPU to lock the bus, but I don&#39;t know when CPU frees the bus?

2. About the whole above code, I don&#39;t understand how this code implements the `Add`?


What does the &quot;lock&quot; instruction mean in x86 assembly?

I want to write a small low level program. For some parts of it I will need to use assembly language, but the rest of the code will be written on C/C++.

So, if I will use GCC to mix C/C++ with assembly code, do I need to use AT&amp;T syntax or can 
I use Intel syntax? Or how do you mix C/C++ and asm (intel syntax) in some other way?

I realize that maybe I don&#39;t have a choice and must use AT&amp;T syntax, but I want to be sure..

And if there turns out to be no choice, where I can find full/official documentation about the AT&amp;T syntax?

Thanks!

Can I use Intel syntax of x86 assembly with GCC?

I don&#39;t understand the `JG/JNLE/JL/JNGE` instructions, which come after CMP.

for example, If I have:

    CMP al,dl
    jg label1

When `al=101; dl =200`.

On what we ask the `jg`? Is it on `al&gt;dl`? or `al-dl&gt;0`?

Same prolbem on the next code:

    test al,dl
    jg label1

I don&#39;t understand what we compare, and on what we ask the &quot;`jg`&quot;.

In other words, I don&#39;t understand when we would jump to label1, and when we wouldn&#39;t.


Assembly - JG/JNLE/JL/JNGE after CMP

I am a beginner to assembly and I don&#39;t know what all the db, dw, dd, things mean.
I have tried to write this little script that does 1+1, stores it in a variable and then displays the result. Here is my code so far:

    .386
    .model flat, stdcall 
    option casemap :none
    include \masm32\include\windows.inc
    include \masm32\include\kernel32.inc
    include \masm32\include\masm32.inc
    includelib \masm32\lib\kernel32.lib
    includelib \masm32\lib\masm32.lib
    .data
    num db ? ; set variable . Here is where I don&#39;t know what data type to use.
    .code
    start:
    mov eax, 1               ; add 1 to eax register
    mov ebx, 1               ; add 1 to ebx register
    add eax, ebx             ; add registers eax and ebx
    push eax                 ; push eax into the stack
    pop num                  ; pop eax into the variable num (when I tried it, it gave me an error, i think  thats because of the data type)
    invoke StdOut, addr num  ; display num on the console.
    invoke ExitProcess       ; exit
    end start

I need to understand what the db, dw, dd things mean and how they affect variable setting and combining and that sort of thing.

Thanks in advance,
Progrmr 

Content Type	Original Author	Original Content on Stackoverflow
Question	MetallicPriest	View Question on Stackoverflow
Solution 1 - C	William Pursell	View Answer on Stackoverflow
Solution 2 - C	codaddict	View Answer on Stackoverflow

Specifying multiple files with LD_PRELOAD

C Problem Overview

C Solutions

Solution 1 - C

Solution 2 - C

Selenium: Can I set any of the attribute value of a WebElement in Selenium?

How do I disable the Internet connection in Android Emulator?

Attributions